1. Field of the Invention
The present invention relates to a feeder and an image forming apparatus including the feeder.
2. Description of Related Art
A feeder used for an image forming apparatus such as an inkjet printer, an electrophotographic printer, a facsimile and a copier includes a paper feed tray called a paper cassette capable of accommodating multiple printing paper sheets, i.e., printing media. The paper feed tray includes a hopper formed of a plate-like body to support stacked media from the bottom. Moreover, a pick-up roller is disposed above the paper feed tray. The pick-up roller rotates while in contact with the uppermost of stacked media placed on the hopper, thereby picking up the uppermost medium from the paper feed tray.
At this point, the hopper pushes up the medium from the bottom, and presses the medium against the pick-up roller. When the pick-up roller rotates under this condition, two or more stacked media may be conveyed downstream at a time by friction between the media. To address this problem, Japanese Patent Application Publication No. 2004-269116, for example, proposes a feeder with a friction member disposed on the upper surface of a hopper at a position facing a pick-up roller (mainly a downstream end portion of the hopper in the medium-feeding direction). This configuration makes more friction between the uppermost medium and the hopper than between the media therein.
However, the aforementioned conventional feeder has the following problem. Specifically, when media are placed in a paper feed tray, the lowermost medium comes into contact with the surface of the friction member. This disturbs the placing of media, so that the lowermost of stacked media thus placed may be misplaced from an intended position. Since the lowermost medium contacts the friction member, it is difficult to adjust the position of the medium via a medium guide provided to the feeder once the media have been placed in the paper feed tray.